Train PEC Requirements/Prerequisites/Check List

Updated September 3, 2021

The Train PEC button hopefully makes it easier to train a Paramount’s periodic error correction. To ensure a successful Train PEC run, you are responsible for the items in the table below.

Please carefully read and follow the items and explanations below.

ItemExplanation
Ensure the mount is reasonably aligned with the pole A reasonable polar alignment is required so the star does not drift out of the track box while collecting periodic error data. Alternatively, use a TPoint model based on a good calibration data set and enable ProTrack. In addition, you can perform “Rough” and “Accurate” polar alignment routines.
Focus your cameraYour optical system needs to be focused. Hint, use @Focus.
You have recently performed an autoguider calibrationTrain PEC depends on a recent, successful autoguider calibration. Why? For starters, this allows Train PEC to automatically determine if the optical system is mirror imaged so resultant PEC table upload is correct, allows you the freedom to have the camera rotated at any angle (more below), provides a basis to re-centering the reference star between the Before PEC and After PEC data collection, etc.

Train PEC will not let you continue until you have successfully performed a “fresh” autoguider calibration.
You have selected a suitable reference star Ensure that you have selected a reference star by double clicking the star. For a description of a good reference star, see Choosing a Good Autoguider Calibration Star in TheSky User Guide. Note that the requirements for choosing a reference star for Train PEC are basically the same.

If you have not already selected a reference star, close this window, return to the Autoguide sub-tab, take a full frame photo, then double click on the desired reference star.

Train PEC will not let you continue until you have “double clicked” a reference star.
You have set a good, short exposure timeMake sure to use a short exposure time, less than or equal to one second, plus ensure the reference star is not too bright nor too dim. A good “maximum” value for the reference star is in the 1000’s. Note the photo’s maximum value is displayed on the Camera window after every exposure to help get this correct. The reference star is too bright if the photos maximum value is near 65000 and too dim if it is under say 1000.
Use a reference star near Dec zero The reference star should be at or near declination zero.
Although stars at higher declinations will give a valid PE calibration, the sensitivity will be compromised.
Use an appropriately sized subframe The default subframe 32×32 is typically too small, 100×100 or 200×200 is normally ok. The subframe size might need to be larger depending on polar alignment, image scale and the number of camera pixels.
The camera may be rotated at any angle Legacy PEC related facilities in TheSky required that the x-axis of the camera be carefully aligned with right ascension/hour angle. This is not a requirement with Train PEC.
The mount can be pointed to either side of the meridianLegacy PEC related facilities in TheSky require you to make a selection as to “Data was collection when mount was pointed west” or not. This is not a requirement with Train PEC and the fore mentioned option is not required/necessary.
Set camera binning to 1 x 1It is recommended to collect PEC data when your camera is at 1×1 binning for the highest resolution. However, Train PEC honor what ever binning you have selected.
Manually enter image scaleMake sure the image scale is accurate/correct on the PEC tab of the Bisque TCS window. Hint, do an Image Link or create a FOV indicator that represents your system.

Note, image scale must match binning. For example, if image scale is 0.75 arcseconds per pixel at 1 x 1 binning, and you would rather use 2 x 2 binning (not recommended), set the camera binning before entering this window, and set image scale to 1.50 arcseconds per pixel.

Train PEC Will…

  • Collect the Before PEC and After PEC data and display the results.
    • Make all necessary settings to accomplish the task:
      • Disable direct guide corrections.
      • Enable camera logging to produce raw tracking logs, not autoguiding logs.
      • Fit a curve to the Before PEC data, re-center the reference star, upload the PEC table to the mount, collect the After PEC data.
      • Automatically turn on Autosave.
      • Show the results of the PE logging.
    • Each Train PEC run saves all relevant data to a run specific folder under the camera’s autosave folder.

Additional Information

Click here to see an actual Train PEC run showing dramatic improvement of a damaged worm with 12 arc seconds of periodic error trained to essentially zero.